1. Field of the Invention
The present invention relates to a structure for mounting a wind receiving member on a wiper device mounted to wipe a windshield of vehicles such as buses, trucks, passenger cars and the like.
2. Background of the Related Art
Conventional wiper devices generally have a drawback that when a vehicle travels at high speed, lift is produced in a wiper blade by an air stream blown against a windshield and the wiping capacity of the wiper blade is lowered by a floating-up phenomenon of the blade caused by the lift. To overcome this drawback, a wind receiving member has been conventionally disposed at the extreme end of a wiper arm with which the wiper blade is provided to thereby press the wiper blade against the windshield by a wind pressure received by the wind receiving member.
However, although it is preferable to mount the wind receiving member at a position as near to the extreme end of the wiper arm as possible to suppress the floating-up phenomenon, a conventional wiper arm only extends to a position where the wiper blade is mounted thereto. To cope with this problem, some wiper devices have an arrangement in which the base end side of a wind receiving member is mounted to the extreme end of a wiper arm. The wind receiving member projects in the direction in which the wiper arm extends as shown in Japanese Utility Model Publication No. 63-32536. In this arrangement, the wiper blade has an increased force for pressing against a windshield because the wind receiving member is disposed at the extreme end of the wiper arm. However, since the wind receiving member is cantilevered at the base end side thereof, when a wind pressure is increased as a vehicle travels at high speed, vibration is produced in the wind receiving member. The vibration causes problems in that not only is the life of the wind receiving member shortened, but also quietness in a compartment is disrupted by a chattering noise made by the vibration. Thus, the wind receiving member arranged as described above cannot achieve the desired effect. To achieve the desired effect, an increase of the width and strength of the wind receiving member and the like must be additionally considered.
On the other hand, other wiper devices have an arrangement in which a support arm for a wind receiving member is projected from a wiper arm and the wind receiving member is mounted to the support arm as shown in Japanese Utility Model Publication Laid-Open No. 3-59263. In this arrangement, however, there arises a new problem that since the dedicated support arm is additionally needed, the number of parts is increased and the assembly is therefore more complex.
Further, since a pantograph-type wiper arm needs a sub-wiper arm for rotating a wiper blade in addition to a main wiper arm, an area cast on a windshield is increased. Therefore, when a wind receiving member is mounted to this type of wiper arm, a position where the wiper arm is mounted on the vehicle must be offset upward taking the interference between the wind receiving member and the frame of the windshield into consideration. Thus a problem arises in that when the wiper arm is not operation, a field of view through a windshield is obstructed and further the size of the wiper arm increased.